1. Field of the Invention
The present invention relates generally to instructional devices, and more particularly, to instructional devices for teaching dental x-ray techniques.
2. General Background
When x-raying teeth, it is important to align the face of the x-ray cone parallel with the face of the x-ray film; otherwise, the x-rays will be inaccurate. Also, it is important to properly set the time and intensity of the x-radiation, so that the film will be neither under exposed nor over exposed.
It is common practice to use live patients when training dental x-ray technicians to use dental x-ray machines. Unfortunately, prolonged exposure to x-radiation is harmful, and in training a dental x-ray technician using the standard methods prevalent today, multiple x-rays are taken, and retaken, and taken again, until the technician learns the proper techniques for x-raying. Thus, in addition to the patient getting exposed to unnecessary x-radiation, he also usually gets tired of sitting still as x-ray after x-ray is taken.
There have been proposals to provide a substitute for a live patient when training dental x-ray technicians. One such proposal is disclosed in U.S. Pat. No. 3,520,060, in which a model of a patient's head is made by covering a human skull with a tissue-equivalent plastic. The head is adapted to be mounted on a dental chair. The mouth of the head opens and closes, allowing x-ray film to be placed in the mouth so technicians can practice taking x-rays of the teeth. Aside from being relatively expensive (human skulls are not cheap) the head must be used in conjunction with a chair and an x-ray machine.
U.S. Pat. No. 4,200,996 discloses another proposal, to provide a substitute for a live patient when training x-ray technicians, which comprises a plastic replica of a human skull, a simulated x-ray cone, and a plurality of slides of x-rays of the teeth of the human skull from which the plastic replica is made. The position of the x-ray cone determines what slide will be visible to the user of the apparatus, the slide which is visible corresponding to an x-ray which would be taken with an actual x-ray cone in that position. This apparatus is relatively expensive and cumbersome. Also it, like the device described above, shows only a single skull, and thus does not help teach technicians to x-ray patients of varying ages in varying stages of development.